Telecommunications apparatuses and methods

1. A method of allocating resources in a mobile telecommunications system, the resources being for a relay node to operate as a terminal-to-terminal relay for device-to-device (D2D) communication between a first terminal and a second terminal, the method comprising: in a case that the first terminal determines that a signal quality for the D2D communication between the first terminal and the second terminal is below a threshold, receiving, by the relay node, a relay request directed to the relay node and sent by the first terminal without receiving another relay request from the second terminal; allocating, in response to receiving the relay request without receiving another relay request from the second terminal, first resources of the resources for the first terminal to communicate via the relay node for the D2D communication with the second terminal; allocating, in response to receiving the relay request without receiving the another relay request from the second terminal, second resources of the resources for the second terminal to communicate via the relay node for the D2D communication with the first terminal; notifying, by the relay node, the first terminal of a first relay notification, the first relay notification indicating an identification of the relay node and the allocated first resources; notifying, by the relay node, the second terminal of a second relay notification, the second relay notification indicating the identification of the relay node and the allocated second resources; and relaying messages, via the relay node and over the first and second resources, between the first and second terminals for the D2D communication, wherein the first terminal performs other D2D communication with a third terminal without relaying messages via the relay node in a case that the a signal quality for the other D2D communication between the first terminal and the third terminal is at or above the threshold.

2. The method of claim 1 , wherein the D2D communication is one of a unicast, a groupcast or a broadcast communication.

3. The method of claim 1 , wherein the allocating the first resources is performed according to at least one of: upon request from the first terminal; upon request from the second terminal; upon receiving instructions from a base station; and upon determination by the relay node.

4. A terminal for use in a mobile telecommunications system and for using a relay node as a terminal-to-terminal relay for device-to-device (D2D) communication between the terminal and a second terminal, the terminal comprising: a transceiver; and processing circuitry configured to determine that a quality for the D2D communication with the second terminal is below a threshold, and control, after determining that signal quality for the D2D communication with the second terminal is below the threshold, the transceiver to transmit a relay request to the relay node, wherein the second terminal does not transmit another relay request to the relay node, in response to transmitting the relay request, the transceiver receives from the relay node one or more grant messages, the one or more grant messages notifying the terminal of an identification of the relay node and of resources allocated for the relay node to relay the D2D communication with the second terminal, and the processing circuitry is further configured to control the transceiver to exchange messages with the second terminal via the relay node and using the allocated resources for the D2D communication, and perform D2D communication with a third terminal without relaying messages via the relay node in a case that the a signal quality for the D2D communication between the first terminal and the third terminal is at or above the threshold.

5. The terminal of claim 4 , wherein the D2D communication is one of a unicast, a groupcast or a broadcast communication.

6. The terminal of claim 4 , wherein the one or more grant messages include: first grant messages broadcast to a first group of terminals, the first grant messages indicating first resources designated for a first group of terminals; and second grant messages broadcast to a second group of terminals, the second grant messages indicating second resources designated for a second group of terminals.

7. The terminal of claim 4 , wherein the resources allocated for the relay node include one or both of: first resources for the terminal to transmit signals to the relay node; and second resources for the relay node to transmit signals to the terminal.

8. A method of allocating resources in a mobile telecommunications system, the resources being for a relay node to operate as a terminal-to-terminal relay for device-to-device (D2D) communication between a first terminal and a second terminal, the method comprising: in a case that the first terminal determines that a signal quality for the D2D communication between the first terminal and the second terminal is below a threshold, receiving, by the relay node, a relay request directed to the relay node and sent by the first terminal without receiving another relay request from the second terminal; identifying, by the relay node, a resource pool for terminal-to-terminal relaying; allocating, in response to receiving the relay request without receiving another relay request from the second terminal, first resources from the resource pool for the first terminal to communicate via the relay node for the D2D communication with the second terminal; allocating, in response to receiving the relay request without receiving the another relay request from the second terminal, second resources from the resource pool for the second terminal to communicate via the relay node for the D2D communication with the first terminal; transmitting, by the relay node, one or more grant messages to the first and second terminals, the one or more grant messages indicating an identification of the relay node and the allocated first and second resources; and relaying messages, via the relay node and over the first and second resources, between the first and second terminals for the D2D device communication, wherein the first terminal performs other D2D communication with a third terminal without relaying messages via the relay node in a case that the a signal quality for the other D2D communication between the first terminal and the third terminal is at or above the threshold.

9. The method of claim 8 , wherein the identifying the resource pool comprises: requesting, by the relay node, a resource pool allocation from a base station; and receiving, by the relay node, an allocation of the resource pool from the base station.

10. The method of claim 9 , wherein the requesting the resource pool allocation is responsive to receiving the relay request from the first terminal.

11. The method of claim 9 , further comprising: releasing, by the relay node, the allocated resource pool by transmitting a resource pool release message to the base station.

12. The method of claim 8 , wherein the identifying the resource pool comprises the relay node identifying a pre-allocated resource pool.

13. The method of claim 8 , wherein the D2D communication is one of a unicast, a groupcast or a broadcast communication.

14. The method of claim 8 , wherein the allocating the first resources is performed according to at least one of: upon request from the first terminal; upon request from the second terminal; upon receiving instructions from a base station; and upon determination by the relay node.

15. The method of claim 8 , wherein the allocating the second resources is performed according to at least one of: upon request from the first terminal; upon request from the second terminal; upon receiving instructions from a base station; and upon determination by the relay node.

16. The method of claim 8 , wherein at least one of the allocating the first resources and the allocating the second resources is based on one or more of: a resource allocation request from one of the first terminal and the second terminal; a determination by the relay node that it will operate as a terminal-to-terminal relay for the D2D communication; and a notification from a base station and/or from one of the first and second terminals that the relay node has been selected for relaying the D2D communication.

17. The method of claim 8 , wherein the transmitting the one or more grant messages comprises at least one of: broadcasting the first resources to a first group of terminals comprising the first terminal; and broadcasting the second resources to a second group of terminals comprising the second terminal.

18. The method of claim 8 , wherein the first resources are for one or both of resources for the first terminal to transmit signals to the relay node and resources for the relay node to transmit signals to the first terminal.

19. The method of claim 8 , wherein the second resources are for one or both of resources for the second terminal to transmit signals to the relay node and resources for the relay node to transmit signals to the second terminal.

20. The method of claim 8 , further comprising releasing first and second sets of resources upon at least one of: determination that the relay node will no longer operate as the terminal-to-terminal relay for the D2D communication between the first terminal and the second terminal; and termination of the D2D communication between the first terminal and the second terminal.